Generally, a strapping machine of a type in widespread use is used for applying a plastic strap in a tensioned loop around a load. Typically, the strapping machine comprises a strap chute for guiding the strap around the load and a strapping head, into which a leading end of the strap is fed. Commonly, the strapping machine is utilized with a strap dispenser, which is arranged to dispense indeterminate lengths of the strap from a coil of strapping. It is known to utilize two strap dispensers, which can be alternately operated, with such a strapping machine.
Generally, the strapping head includes means for advancing the strap along the strap chute, around the load, until the leading end returns to the strapping head, and means for retracting the strap so as to pull the strap from the strap chute and to produce a tension in the strap around the load. Generally, moreover, the strapping head includes means for securing the strap in a tensioned loop around the load either by welding the strap to itself at its overlapping portions or by applying a metal seal to the overlapping portions via the strapping head and means for severing the strap in the tensioned loop from the remaining strap.
Furthermore, it is typical for the strapping head to comprise means for sensing whether the leading end of the strap being advanced has reached a predetermined location relative to the strapping head, within a predetermined time during an operating cycle of the strapping machine. Generally, if the strap becomes jammed within the strap chute or exits the strap chute before reaching the sensor, the leading end of the strap is not sensed as having reached the predetermined location within the predetermined time.
It is known to arrange the strapping head so that, if the leading end of the strap is not sensed as having reached the predetermined location within the predetermined time, the strap is retracted by the retracting means of the strapping head. It is known for a user manually to sever any deformed portion of the retracted strap from the remaining strap. It is known for the leading end of the remaining strap from the same dispenser or the leading end of a different strap from a different dispenser to be manually or automatedly fed into the strapping head for a following cycle.